The present invention relates to an automatic tool changing apparatus (ATC apparatus) for use in a machine tool.
According to a conventional tool changing apparatus such as a machining center, a swing arm which exchanges a tool between a tool magazine and a main spindle is disposed on a stationary member such as a column. Further, consequential tool exchanging operations such as tool holding by tool holding claws, tool removal, tool rotation by 180 degrees, new tool insertion, and tool clamping are each driven by hydraulic cylinders, and every one step of operation is acknowledged by a limit switch for the subsequent step of operation.
With this construction, the main spindle head is required to be displaced to the tool changing position, that is, the position at which the swing arm is disposed. This displacement of the main spindle head may prolong the entire operation.
Further, during the tool exchanging operation, termination of each one of the steps is verified and then the next step is conducted. Such sequencial steps do not permit overlapping steps, so that time consuming operation results. Furthermore, since the hydraulic cylinders are employed as driving sources, it would be rather difficult to control acceleration or deceleration during operation, and high speed operation is not attainable in the conventional apparatus.
Examples of the conventional tool changing apparatus are described in Japanese patent application publications(kokai) Nos. 68-45836, 60-228047, 61-164743, and Japanese patent publication No. 69-32257.